What is the cause of a cardiac myxoma (a type of benign cardiac tumor)?

From the Guidelines

Myxomas are primarily caused by abnormal growth of mesenchymal cells in the heart, most commonly in the left atrium, with the majority occurring sporadically without a clear trigger, although about 10% are associated with genetic conditions, particularly Carney complex 1. The development of myxomas is not fully understood, but it is believed to involve the abnormal growth of multipotent mesenchymal cells that normally produce the heart's gelatinous protective lining.

• Key factors that may contribute to the development of myxomas include:
  • Genetic conditions, such as Carney complex, which is caused by mutations in the PRKAR1A gene 1
  • Inflammation, viral infections, or prior cardiac surgery, which may trigger myxoma development in predisposed individuals, although these associations remain speculative 1
• Unlike many other tumors, myxomas do not typically result from lifestyle factors or environmental exposures. The abnormal cells in myxomas produce excessive mucopolysaccharides, creating the characteristic gelatinous mass that can obstruct blood flow, embolize, or cause constitutional symptoms through cytokine production. Early detection and surgical removal are essential for treatment, as myxomas can lead to serious complications, including stroke and embolism, if left untreated 1. It is worth noting that the exact cause of myxomas is still not fully understood and more research is needed to determine the underlying mechanisms of their development, as stated in the 2021 guideline for the prevention of stroke in patients with stroke and transient ischemic attack 1.

From the Research

Cause of Cardiac Myxoma

The cause of cardiac myxoma is still controversial, but the current view centers around origin from the primitive pluripotent mesenchymal cells 2.

• Cardiac myxomas may arise from mesenchymal cardiomyocyte progenitor cells, as indicated by the presence of cardiomyocyte-specific transcription factor genes 3.
• Genetic factors, such as mutations in the PRKAR1A gene, play a role in the development of familial cardiac myxomas, particularly in the context of Carney complex 4, 5.
• Chromosomal abnormalities involving chromosomes 2p, 12, and 17q have been reported in hereditary cardiac myxoma, but no genetic abnormalities of these loci were found in sporadic cases 3.
• Various cytokines and growth factors, such as vascular endothelial growth factor, basic fibroblast growth factor, monocyte chemotactic protein-1, and interleukin-6, are involved in tumor growth and angiogenesis 3.

Familial Cardiac Myxoma

Familial cardiac myxomas are related to Carney complex, a multiple neoplasia and lentiginosis syndrome, and are caused by mutations in the PRKAR1A gene 4, 5.

• Less than 10% of cardiac myxomas are familial, and these cases are often associated with Carney complex 4.
• Genetic testing can detect mutations in the PRKAR1A gene, allowing for early diagnosis and treatment of familial cardiac myxomas 4, 5.

Sporadic Cardiac Myxoma

The exact cause of sporadic cardiac myxoma is still unknown, but it is thought to arise from the primitive pluripotent mesenchymal cells 2.

• Sporadic cardiac myxomas are the most common type, accounting for more than 90% of cases 4.
• The role of interleukin interactions in the pathophysiology of cardiac myxoma is still being studied, and may lead to embolic complications, aneurysms, and CNS involvement 6.